Question

Please give me fast! Please​

Answer 1

To Factorise :

The expression:

• 22(x⁴-x³-20x²)

Solution :

22(x⁴-x³-20x²)

= 22x²(x²-x-20)

= 22x²[(x)²-[5-4]x-(5×4)]

= 22x²[ (x)² + [-5+4]x +(-5×4) ]

Observe that this expression can now be factorised with the identity:

• (x+a)(x-b)=x²+(a+b)x+ab

so, 22x²[ (x)² + [-5+4]x +(-5×4) ]

= 22x²[(x-5)(x+4)]

= (22x²)(x-5)(x+4)

so, Varun should use the identity:

• (x+a)(x-b)=x²+(a+b)x+ab

hence, option d) is correct